JPH05199595A - Acoustic field reproducing device on vehicle - Google Patents

Abstract

PURPOSE:To give the same frequency characteristic and sound image localization as a front seat to a rear seat by providing a speaker system, which limits the radiation area of an acoustic power, for the rear seat. CONSTITUTION:Four directivity control speaker systems 4 to 7 which have sharp directional patterns to limit the radiation area of the acoustic power are provided per channel in parallel for two listeners in front seats and those in rear seats. A digital filter 8 which is provided with a coefficient to correct the time of the response from a speaker system 3 for low-pitched sounds and to cancel the response from speaker systems 4 and 5 for high-pitched sounds for listeners in front seats is provided in the preceding stage of input to speaker systems 6 and 7 for high-pitched sounds for listeners in rear seats. Thus, the time response from the speaker system 3 for low-pitched sounds is matched even in listening positions of rear seats, and the acoustic field characteristic which is not affected by the response from speaker systems 4 and 5 for high- pitched sounds for listeners in front seats is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle-mounted sound field reproducing apparatus which gives the same frequency characteristics and sound image localization to the rear seats as the front seats when reproducing sound in a vehicle interior.

[0002]

2. Description of the Related Art Conventionally, sound field characteristics such as frequency characteristics and sound image localization have not been considered so much for listeners in the back seat, and sound field characteristics equivalent to those of listeners in the front seat cannot be obtained. It was difficult.

FIG. 5 shows a layout of a speaker system in a conventional vehicle-mounted sound field reproducing apparatus. 3 is a bass speaker system, 9 is a dashboard, 10 is a driver's seat, 1
1 is a passenger seat, 12 is a rear seat, and 16 is a rear speaker. In the configuration as shown in (FIG. 5), the sound field characteristic of the rear seat 12 at the listening position is strongly controlled by the response from the rear speaker 16 arranged in the rear part of the vehicle.

[0004]

However, the sound field characteristic of the rear speaker 16 placed on the rear tray has peaks and dips in the frequency characteristic due to phase interference due to near reflection with the rear window. In addition, since the sound source is located behind the listener, the sound image is also strongly localized behind the listener. Furthermore, the response from the left and right rear speakers 16 at the listening position of the rear seat 12 becomes an unbalanced response because the distance to the listening position greatly differs between the left and right, and stereo balanced reproduction becomes very difficult.

The present invention realizes the stereo front localization of the sound image by improving the frequency characteristics by providing a speaker system capable of limiting the area where the acoustic power is radiated even to the listener in the back seat, and the listener in the front seat. The purpose is to obtain sound field characteristics equivalent to.

[0006]

In order to achieve this object, the present invention divides a stereo input signal into bands, and limits a region where sound power is radiated in a high frequency band which is a dominant factor for sound image localization. Directivity control speaker systems having sharp directional characteristics are provided in parallel for each of two listeners in the front seat and two listeners in the rear seat, four per channel.

[0007]

With the above-described structure, the present invention can realize frequency characteristics and sound image localization equivalent to those of the front seats even in the rear seats in the vehicle interior sound field.

[0008]

EXAMPLES Specific examples will be described in detail below.

FIG. 1 is a block diagram of a vehicle-mounted sound field reproducing apparatus according to the first embodiment of the present invention. 1 is a stereo input terminal, 2 is a frequency selection filter, 3 is a low-pitched speaker system, 4 is a high-pitched speaker system for listeners in the driver's seat, 5 is a high-pitched speaker system for listeners in the passenger seat,
6 is a loudspeaker system for the listener on the right side of the rear seat, 7 is a loudspeaker system for the listener on the left side of the rear seat, 8 is a digital filter, 9 is a dashboard,
10 is a driver's seat, 11 is a passenger seat, and 12 is a rear seat.

The operation of the vehicle-mounted sound field reproducing device constituted by the above system will be described.

The signal stereo-inputted to the stereo input terminal 1 is band-divided at an arbitrary frequency f within the audible band by the frequency selection filter 2 for each of the L and R channels.
The division frequency f is the high frequency speaker system 4, 5, 6, 7
It is determined by the directional characteristics of the, but the details will be described later. The low frequency band output of the frequency selection filter 2 is radiated into the vehicle interior from the bass speaker system 3.

As shown in FIG. 2, in this embodiment, the dashboard 9 is mounted downward on the lower side of the dashboard 9 so that no sound directly reaches the listening position close to the speaker system. As a result, in the low frequency band, indirect sound dominant response occurs in both the channel near the listening position and the channel far from the listening position, and a sound field with a sense of spaciousness is formed.

Next, the high-frequency band output of the frequency selection filter 2 is connected in parallel to the high-pitched speaker systems 4 and 5 for listeners in the front seats and the high-pitched speaker for listeners in the rear seats. It is emitted from the systems 6 and 7 into the passenger compartment. As shown in (FIG. 1) and (FIG. 2), the high-pitched speaker systems 4 and 5 for the front seat listeners are on the dashboard 9, and the high-pitched speaker systems 6 and 7 for the rear seat listeners are It is installed by embedding it in the ceiling.

FIG. 3 shows the structures of the high-pitched speaker systems 4, 5 for the front seat listener and the high-pitched speaker systems 6, 7 for the rear seat listener. 13 is a horn opening portion linearly arranged at equal intervals, 14 is a horn portion,
Reference numeral 15 is a horn driver. By adopting such a structure, the horn driver portion 15, which requires a large volume at the time of installation, can be installed in an empty space of the vehicle body, and restrictions on the installation position in the vehicle interior can be reduced. Become. Then, the acoustic power is guided to the horn opening 13 by the horn 14, and the horn opening 13 is provided at the acoustically desirable position, so that the acoustic power can be radiated from the acoustically desirable position into the vehicle interior.

Further, the high-pitched speaker systems 4, 5 for listeners in the front seats and the high-pitched speaker systems 6, 7 for listeners in the rear seats have sharp directional characteristics that can limit the region from which acoustic power is radiated. As shown in (FIG. 1), the directional control speaker system has the directional axes of the L and R channels directed to the respective listening positions. Here, the effect of using the directivity control speaker system having a sharp directional characteristic in the vehicle interior sound field will be described.

In sound reproduction, the reflected wave may disturb the frequency characteristic at the listening position, which may be a factor to impair the localization of the sound image. In particular, since the interior space of the vehicle has a small space and a reflective wall such as glass exists near the listening position, the primary or secondary reflected waves in the vehicle interior sound field greatly affect the direct waves.

FIG. 6 shows calculated values of the echo time pattern in the sound field in the vehicle interior. 2 reflected waves for direct waves
It can be seen with a delay of ~ 3msec. Seen from the temporal order, these responses are close to the time difference between both ears, and act as phase interference of direct waves, disturb the frequency characteristics at the listening position, and hinder the localization of the sound image.

FIG. 7 shows an echo time pattern when a sharp directional characteristic is given to the sound source under the same calculation conditions as the above (FIG. 6). Compared with (Fig. 6), the temporal pattern of the response does not change because the geometric shape of the space is the same,
It can be seen that the energy level in the direction away from the directional axis of the sound source is small due to the sharp directional characteristics, and the level of the unnecessary reflected wave at the listening position is lowered. Therefore, by sufficiently sharpening the directivity of the sound source, the phase interference of the reflected wave with the direct sound can be reduced.

FIG. 8 shows measured values of directivity characteristics of the directivity control speaker system shown in FIG. In FIG. 1, the high-pitched speaker system 4 on the dashboard is shown.
The angle θ between the listening position of the driver's seat and the listening position of the passenger seat at the mounting position of No. 5 is about 35 °. Therefore, if the division frequency f of the frequency selection filter 2 is set to 5 kHz, as shown in FIG.
A directional characteristic of 5 dB is realized.

Further, the distance from the mounting position of the high-pitched speaker systems 4 and 5 on the driver's seat side on the dashboard 9 to the listening position of the driver's seat 10 and the distance to the listening position of the passenger seat 11 are 840 mm and 1260 mm, respectively. In that case, the vehicle interior space is left-right asymmetric with respect to the listening position, and therefore the arrival times of the left and right signals are deviated by the path difference at the listening position. Therefore, in this embodiment, as shown in FIG. 1, the time difference τ = 1.
The electrical delay means 17 for correcting 23 msec is provided in the front stage of the speaker system in which the directional axis is oriented to the listening position close to each mounting position. by this,
At each listening position, the time response of the direct waves from the left and right channels is adjusted. Further, as another embodiment, instead of the electrical delay means 17, the length of the horn part 14 of the high-pitched speaker system shown in FIG. 3 is corrected by the path difference to provide a simple acoustic delay means. You can That is, if the length of the horn portion 14 of the speaker system whose directional axis is oriented to the listening position close to each of the mounting positions is made 420 mm longer than the length of the horn portion 14 of the other speaker system, an electrical delay will occur. An effect equivalent to that of the means 17 can be obtained.

In FIG. 1, in particular, before inputting to the high-pitched speaker systems 6 and 7 for listeners in the rear seats, time correction with the response from the low-pitched speaker system 3 and reception of the front seats are performed. High-pitched speaker system for listeners 4, 5
A digital filter 8 having a coefficient for canceling the response from is provided so that the time response with the low-pitched speaker system 3 is adjusted even at the listening position of the rear seat, and the high-pitched sound for the listener of the front seat is provided. Sound field characteristics that are not affected by the responses from the speaker systems 4 and 5 can be obtained.

FIG. 4 shows an on-vehicle sound reproducing device according to a second embodiment of the present invention, in which a bass speaker system 3 is provided under a dashboard 9 for a high tone for a listener in a front seat. Speaker systems 4 and 5 are installed on the dashboard 9, and treble speaker systems 6 and 7 for listeners in the rear seats are installed on the back surface of the front seats. In addition, a high-pitched speaker system 4 for listeners in the front seats
5 and loudspeaker system 6 for the rear seat listeners
A speaker system 7 is composed of a set of a plurality of driver units arranged in a straight line at equal intervals.

[0023]

INDUSTRIAL APPLICABILITY As described above, the present invention divides a stereo input signal into bands, and has a directivity having a sharp directivity characteristic in which a region emitting sound power can be limited in a high frequency band which is a dominant factor in sound image localization. The sex control speaker system is provided in parallel for each of the two front seat listeners and the two rear seat listeners, four per channel. As a result, it is possible to achieve the same frequency characteristics and sound image localization as those of the front seats even in the rear seats in the vehicle interior sound field.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a first embodiment of the present invention.

FIG. 3 is a structural diagram of a speaker system according to a first embodiment of the present invention.

FIG. 4 is a configuration diagram of a second embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional example.

FIG. 6 Calculation result of echo time pattern of omnidirectional speaker in vehicle interior

FIG. 7: Calculation result of echo time pattern of directional control speaker in vehicle interior

FIG. 8 is a frequency characteristic diagram of the directional control speaker.

[Explanation of symbols]

1 Stereo input terminal 2 Frequency selection filter 3 Low-pitched speaker system 4 High-pitched speaker system for driver's seat listener 5 High-pitched speaker system for passenger seat listener 6 High-pitched sound for driver seat listener on rear seat Loudspeaker system 7 High-pitched speaker system for listeners on the passenger side of the rear seat 8 Digital filter 9 Dashboard 10 Driver's seat 11 Passenger seat 12 Rear seat 13 Horn opening 14 Horn part 15 Horn driver 16 Rear speaker 17 Electrical Delay means

Claims (12)

[Claims] 1. A frequency selection filter for dividing a stereo input signal into two bands at an arbitrary frequency f within an audible band, a bass speaker system for radiating acoustic power below the frequency f, and above the frequency f. A high-pitched speaker system having an elongated rectangular sound source shape that limits a region in which sound power is radiated in a band, and the high-pitched speaker system includes two listeners, a front seat and two listeners. An in-vehicle sound field reproducing device, which is provided in parallel in the vehicle, four for each listener in a channel. 2. The in-vehicle sound field reproducing apparatus according to claim 1, wherein the high-pitched speaker system is a speaker system having an elongated rectangular diaphragm. 3. The on-vehicle sound field reproducing apparatus according to claim 1, wherein the high-pitched speaker system is a speaker system including a horn having an elongated rectangular opening. 4. A frequency selection filter for dividing a stereo input signal into two bands at an arbitrary frequency f within the audible band, a bass speaker system for radiating acoustic power below the frequency f, and above the frequency f. A treble speaker system configured by a set of a plurality of sound sources linearly arranged at equal intervals that limit a region where sound power is radiated in a band, and the treble speaker system is a front seat in a vehicle interior. An on-vehicle sound field reproducing device, which is provided in parallel in the vehicle compartment, four for each listener and two listeners in the back seat. 5. The in-vehicle sound field reproducing apparatus according to claim 4, wherein the high-pitched speaker system is a speaker system configured by a set of a plurality of driver units linearly arranged at equal intervals. 6. A speaker system for high-pitched sound has one horn driver and a plurality of horns for transmitting the acoustic output of the horn driver, and the openings of the horns are linearly arranged at equal intervals. The vehicle-mounted sound field reproducing device according to claim 4, wherein 7. A frequency selection filter for dividing a stereo input signal into two bands at an arbitrary frequency f within the audible band, a bass speaker system for radiating acoustic power below the frequency f, and above the frequency f. A treble speaker system in which the shape of a sound source is a long and narrow rectangular shape that limits an area for radiating acoustic power in a band, and the treble speaker system includes two listeners in a front seat and two listeners in a rear seat. 4 units per channel are provided in parallel for each listener, and the time of the response from the low-pitched speaker system is input before the input of the high-pitched speaker system installed for the rear seat listener. Provided is a digital filter having a coefficient for correcting and canceling the response from the high-pitched speaker system installed for the listener in the front seat. An in-vehicle sound field reproducing device characterized in that 8. The in-vehicle sound field reproducing apparatus according to claim 7, wherein the high-pitched speaker system is a speaker system having an elongated rectangular diaphragm. 9. The in-vehicle sound field reproducing apparatus according to claim 7, wherein the high-pitched speaker system is a speaker system including a horn having an elongated rectangular opening. 10. A frequency selection filter for dividing a stereo input signal into two bands at an arbitrary frequency f within an audible band, a bass speaker system for radiating acoustic power below the frequency f, and above the frequency f. A treble speaker system configured by a set of a plurality of sound sources linearly arranged at equal intervals that limit a region in which sound power is radiated in a band, and the treble speaker system is provided in a front seat of a vehicle interior. For each low-pitched speaker system before the input of the high-pitched speaker system, which is installed in parallel for four listeners and two listeners in the rear seat, four per channel in parallel. A time correction is performed with the response from the speaker system, and a coefficient for canceling the response from the high-pitched speaker system installed for the listener in the front seat is set. An in-vehicle sound field reproducing device, characterized by comprising a digital filter provided. 11. The in-vehicle sound field reproducing apparatus according to claim 10, wherein the high-pitched speaker system is a speaker system configured by a set of a plurality of driver units linearly arranged at equal intervals. 12. A loudspeaker system comprising a horn driver and a plurality of horns for transmitting acoustic output of the horn driver, wherein the horn openings are linearly arranged at equal intervals. The in-vehicle sound field reproducing device according to claim 10, wherein